Letter to the Editor : Bevacizumab and Triamcinolone for Branch Vein Occlusion

( Ian Yat Hin Wong ) 대한안과학회 2010 Korean Journal of Ophthalmology Vol.24 No.3

Behaviour of Composite Cellular Steel - Concrete Beams at Elevated Temperatures

Vuiyee Bernice Wong,Ian Burgess,Roger Plank 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.1

The behaviour of composite cellular floor beams is becoming important as such members are increasingly used in multistorey buildings. In the event of fire, this issue becomes increasingly critical, particularly for exposed steelwork. In a fire situation, a composite beam has a much higher perimeter area exposed to fire in its lower web-flange section than in the upper web-flange section, and so the temperature distribution across a composite beam is usually non-uniform. The reduction in fire of the strength and stiffness of the material properties of the perforated steel beam, as well as differential thermal expansion, therefore becomes an important influence on the overall behaviour of the composite beam. The objective of this research is to enhance the level of understanding of the generic behaviour of composite cellular floor beams in fire conditions. In this paper, three-dimensional nonlinear finite element models of composite cellular floor beams have been developed, taking into consideration the influence of the changes in material properties with temperature. Experimental data from furnace tests on cellular composite floor beams obtained from previous research work has been used to validate the FE models. An analytical model based on existing design guides is also presented in this paper. It is concluded that finite element analysis results are in good agreement with the experimental data, and all the failure modes have been accurately predicted. The proposed simplified analytical methods show reasonable agreement with the test and FE results, and are always conservative. The behaviour of composite cellular floor beams is becoming important as such members are increasingly used in multistorey buildings. In the event of fire, this issue becomes increasingly critical, particularly for exposed steelwork. In a fire situation, a composite beam has a much higher perimeter area exposed to fire in its lower web-flange section than in the upper web-flange section, and so the temperature distribution across a composite beam is usually non-uniform. The reduction in fire of the strength and stiffness of the material properties of the perforated steel beam, as well as differential thermal expansion, therefore becomes an important influence on the overall behaviour of the composite beam. The objective of this research is to enhance the level of understanding of the generic behaviour of composite cellular floor beams in fire conditions. In this paper, three-dimensional nonlinear finite element models of composite cellular floor beams have been developed, taking into consideration the influence of the changes in material properties with temperature. Experimental data from furnace tests on cellular composite floor beams obtained from previous research work has been used to validate the FE models. An analytical model based on existing design guides is also presented in this paper. It is concluded that finite element analysis results are in good agreement with the experimental data, and all the failure modes have been accurately predicted. The proposed simplified analytical methods show reasonable agreement with the test and FE results, and are always conservative.

Anti-VEGF Monotherapy versus Combined Anti-VEGF and Endpoint Management Laser for Diabetic Macular Edema (END-DME Study)

Miho Nozaki,Ian Y Wong,Ryo Kawasaki,Joo Eun Lee,Yoshihiro Takamura,Ji Eun Lee,Shigeo Yoshida,Jae Pil Shin,Teruyo Kida,Woohyok Chang,Eiko Tsuiki,Hidetaka Noma,Kiyoshi Suzuma 한국망막학회 2022 Journal of Retina Vol.7 No.2

Purpose: To compare the efficacy of a combination of anti-vascular endothelial growth factor (VEGF) and endpoint management (EpM) grid laser versus monotherapy with anti-VEGF in the management of diabetic macular edema (DME). Methods: This was a prospective, multicenter, open-label, nonrandomized interventional study (NCT02462304). Anti-VEGF therapy consisted of one initial injection administered pro re nata in both groups. EpM laser was performed within 1 month after the first anti-VEGF injection. The main outcome evaluated was the number of anti-VEGF injections performed in 6 months. Best-corrected visual acuity (BCVA) and central foveal thickness (CFT) were also evaluated monthly. The anti-VEGF agent used in Japan and Hong Kong was ranibizumab, while bevacizumab was used in Korea. Results: This study enrolled a total of 42 subjects, with 19 (45.2%) allocated to the monotherapy arm and 23 (54.8%) allocated to the combination arm (EpM group). Overall, there was no significant difference in the number of injections between patients in the two groups (+0.12, p = 0.81). Mixed regression analysis with all the covariates plus an interaction term for the ranibizumab/bevacizumab and the monotherapy/combination arm showed that the EpM group needed 0.94 less injections (95% confidence interval [CI], -1.73 to -0.15; p = 0.02). The logarithm of the minimum angle of resolution BCVA at 24 weeks was significantly improved in the monotherapy arm (p = 0.03), but not in the EpM group (p = 0.09). CFT at 24 weeks was significantly improved in both groups (p < 0.01). Conclusions: These data suggest that combination therapy with the EpM laser may be effective for reducing the number of anti-VEGF injections required for DME treatment.

Case Report : Congenital Glaucoma from Sturge-Weber Syndrome: A Modified Surgical Approach

( Nancy Shi Yin Yuen ),( Ian Yat Hin Wong ) 대한안과학회 2012 Korean Journal of Ophthalmology Vol.26 No.6

Sturge-Weber syndrome (SWS) is a rare congenital neurocutaneous disorder that causes congenital glaucoma. Previous experiences have shown that drainage procedures are often required to control associated glaucoma. The conventional surgical approach in trabeculectomy carries a significant risk of intraoperative expulsive hemorrhage. Here, we describe a modified approach of the conventional trabeculectomy technique, which may lower the risk of expulsive hemorrhage. A viscoelastic device was employed to maintain a steady intraocular pressure throughout the procedure. Details of the surgical technique and material used are described. One patient with congenital glaucoma associated with SWS underwent a successful trabeculectomy using the modified technique. Postoperative intraocular pressure was successfully reduced and no intraoperative complications occurred. We describe a successful case of trabeculectomy in a SWS case where a modified technique was applied.

Modeling and analysis of rotating plates by using self-sensing active constrained layer damping

Zhengchao Xie,Pak Kin Wong,Ian Ian Chong 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.10

This paper proposes a new finite element model for active constrained layer damped (CLD) rotating plate with self-sensing technique. Constrained layer damping can effectively reduce the vibration in rotating structures. Unfortunately, most existing research models the rotating structures as beams that are not the case many times. It is meaningful to model the rotating part as plates because of improvements on both the accuracy and the versatility. At the same time, existing research shows that the active constrained layer damping provides a more effective vibration control approach than the passive constrained layer damping. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate. Unlike previous ones, this finite element model treats all three layers as having the both shear and extension strains, so all types of damping are taken into account. Also, the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator. Then, a proportional control strategy is implemented to effectively control the displacement of the tip end of the rotating plate. Additionally, a parametric study is conducted to explore the impact of some design parameters on structure’s modal characteristics.

Cardiac evaluation for end-stage kidney disease patients on the transplant waitlist: a single-center cohort study

Swati Vijayan,Quan Yao Ho,Choong Hou Koh,Ian Tatt Liew,Sobhana Thangaraju,Ningyan Wong,Yann Shan Keh,Zi Hui Sharel Ong,Jia Qin Tan,Khung Keong Yeo,Terrance Siang Jin Chua,Terence Kee 대한이식학회 2022 Korean Journal of Transplantation Vol.36 No.3

Background: Cardiac evaluation before deceased donor kidney transplant (DDKT) remains a matter of debate. Data on Asian countries and countries with prolonged waiting times are lacking. This study aimed to assess the outcomes of patients referred for DDKT after a cardiac evaluation at an Asian tertiary transplant center. Methods: This single-center retrospective review analyzed patients who were referred for waitlist placement and underwent cardiac stress testing between January 2009 and December 2015. Patients with cardiac symptoms were excluded. The primary outcome was three-point major adverse cardiovascular events (MACE), a composite of non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death. Results: Of 468 patients referred for DDKT, 198 who underwent cardiac stress testing (myocardial perfusion studies in 159 patients and stress echocardiography in 39 patients) were analyzed. MACE occurred in 20.7% of the patients over a median follow-up of 4.6 years. Cardiac stress tests were positive for ischemia in 19.7% of the patients. Coronary angiography was performed in 63 patients, including 29 patients with diabetic kidney disease and negative cardiac stress tests. Significant coronary artery disease (CAD) was detected in 27 patients (42.8%), of whom 18 underwent revascularization. MACE was associated with significant CAD on coronary angiography in the multivariable analysis. Cardiac stress test results were not associated with MACE. Amongst diabetic patients who had negative cardiac stress tests, 37.9% had significant CAD on coronary angiography. Conclusions: The cardiovascular disease burden is significant amongst DDKT waitlist candidates. Pretransplant cardiac screening may identify patients with significant CAD at higher risk of MACE.